A key obstacle in the development of effective adolescent HIV services programs is the lack of adolescent- specific HIV prevalence and service use data. Population surveys and country reports do not recognize adolescence as a distinct developmental stage; instead adolescents are grouped with young adults and called youth (i.e., 15-24 years). Available data indicate that an estimated 5 million youth are HIV infected worldwide and 75% of them live in sub-Saharan Africa. However, in contrast to young adulthood, adolescence is a period of transition characterized by major physiological, intellectual and psychosocial changes. Thus, the testing, treatment, and care needs of HIV-infected youth in mid to late adolescence (i.e., 15-19 year olds) are likely to differ substantiall from those of young adults (i.e., 20-24 years). This study focuses on adolescents because, although research indicates that this group faces a high risk of infection, inadequate attention has been paid to effective ways to identify and link the infected to care. While little is known about how to engage adolescents in HIV services, evidence suggests that available services are insufficient for this group. Few adolescents test for HIV and little is known about the proportion of adolescents in urgent need of HIV care and treatment globally receiving these services. As a group, adolescents do not routinely access provider-initiated HIV testing and counseling unless they are pregnant or in very poor health. It is not known how many youth are receiving HIV care because there are no systems that track linkage to care among those who test positive and are referred to care in Kenya. Research, however, suggests that younger infected individuals are less likely to be enrolled in care than older individuals, suggesting the need to develop more universal strategies for identification, care and treatment. The proposed study setting is Siaya District in Nyanza Province, which is the region with the highest HIV prevalence in Kenya. The Luos, comprising more than 90% of the Siaya District population, have the highest HIV and orphan prevalence of all ethnic groups in Kenya. The 2 specific study aims are: 1) To estimate HIV prevalence among Siaya District adolescents aged 15-19 years and the proportion of those infected engaged in care. Researchers will use two recent and reliable population-based data sources to estimate prevalence among Siaya adolescents and provider data to estimate the proportion receiving and adhering to HIV services. These data will provide the first credible estimate of the size of the gap between adolescents infected and those receiving care. Because the gap is expected to be large, this new information can elevate adolescent HIV care as a priority on the public agenda and serve as a baseline for intervention research. 2) To identify the obstacles and most promising strategies to identify and link HIV positive adolescents to care. Investigators will conduct qualitative interviews with key informants in at least 15 clinics with substantial experience testing and linking adolescents to care in Siaya District. They will also interview up to 80 HIV positive adolescents 15-19 years and their parent or guardian about their perceptions of barriers and possible facilitators to engagement in HIV services. This R21 research study addresses a highly vulnerable population that has been largely neglected by HIV researchers and policy makers.